The items you listed aren't a problem at all. Read some articles about various companies in Wikipedia. How can you NOT mention a company's title and products in an article about that company?
The answer to your second question - "If I do make a mistake, may a company sue me?" - is YES. It's even possible that they could sue you even though you do NOT make a mistake. Do some research on "SLAP lawsuits." However, it's hard to imagine how any company would even think about suing you for mentioning their name or telling readers what that company does.
The answer to the third question is less clear (for me). Publishing the names of company employees might be illegal, unless they're "public personages." Publishing personal details about employees would be even more dangerous.
If you had access to "trade secrets" that could damage a company's business, that might be another problem. You certainly wouldn't want to publish anything that's legally protected (trademark, copyright, patent, etc.) without getting permission or doing your homework.
Again, do some online research. See how easy it is to track down various corporations' names, addresses, number of employees, etc. The information is widely available.